As well as money, treasures and gems, many Grophs place great value in secrets and information. These secrets are represented by by Whispered Secrets and Deadly Secrets.
You can gain Whispered Secrets in a number of ways, such as in the Undertown, from The Queen or from missions. Deadly Secrets come from more dangerous missions, and can be converted into multiple Whispered Secrets if you wish. You can trade Whispered Secrets with the Underking, if you have enough Criminality to visit him.
Other forms of secrets come in the form of Royal Scrolls and Royal Pardons, which can be used to remove the criminality from a Groph. You can get these from the Royal Chamberlain in the Castle Keep.